The invention relates to sealing structure for rotary equipment of the type in which a relative large-diameter cylindrical shell is supported with its axis horizontal by inlet and discharge housings, arrangements of this character being commonly employed in the treatment--e.g., heating, cooling, drying, etc.--of granular and like material, as by heating, cooling, etc. tubing extending through the shell. Because the size of the shell militates against the manufacture and maintenance thereof as a perfect cylinder, special sealing problems exist between the shell and its fixed related housings, the out-of-round condition of the shell magnifying the possibility of material leakage at the junctions of the shell and housings. These problems have been met, in large part, by the provision of one form or another of segmented seal ring at the areas in question, whereby the sealing ring can accommodate and follow the out-of-round condition of the shell. Copending U.S. patent application Ser. No. 618,984, filed June 8, 1984, now U.S. Pat. No. 4,502,702, contains as its subject matter a form of segmented seal ring upon which the present invention comprises one or more improvements.
In the structure referred to above, each pair of neighboring segments is provided with overlapping end portions that cooperate to form a gap and radial interface at the junction of the segments. As the cylindrical shell rotates, its slightly "ovalized" shape is accommodated by the segments as they move circumferentially and radially in response to "high spots" on the shell. Thus, the circumferential dimension at each gap constantly changes. The presence of the gaps invites the entrance of material into the gaps, each of which is normally formed by spaced apart parallel edges of the neighboring end portions of the segments. Material, especially of soft, relatively moist nature, tends to pack solidly in the gaps and ultimately creates a situation in which the seal ring not only increases in diameter but loses its flexibility and thus its sealing effectiveness is diminished if not destroyed.
According to the present invention, packing of material in the gaps is prevented or at least materially minimized by providing each gap with a relatively wide mouth at the arcuate inner edges of the segment end portions where these arcuate edges ride the shell, together with a sealing element blocking the gap at the junction of the mouth and the adjoining narrow part of the gap. Hence, the material has more room to work its way out of the mouth, especially since the mouth is shaped with radially outwardly converging walls. The location of the flexible sealing element at the point noted prevents the material from entering and packing into that portion of the gap radially beyond the mouth, that portion being conveniently formed by closely circumferentially spaced apart parallel radial edges. Further features and advantages of the invention will become apparent to those versed in the art as preferred embodiments are disclosed in detail in the ensuing description and accompanying sheets of drawings.